Not Applicable
1. Field of the Invention
The present invention relates to golf equipment and, more specifically, to a diagnostic golf club having the ability to make quantitative measurements of specific mechanical or physical properties of the golf club during a golf swing. Strain gauges are provided on the exterior of the shaft of the golf club and a memory device is provided within the interior containing data descriptive of the measured properties.
2. Description of the Related Art
Various data measuring and collecting devices and methods are used for analyzing a golf club during a golf swing. In a similar manner, the effectiveness of a golf ball impact with the golf club during the golf swing can be measured in terms of initial launch conditions. Such launch conditions include the initial velocity, launch angle, spin rate and spin axis of the golf ball. These launch conditions are determined principally by the velocity of a club head at impact and the loft and angle of a club face relative to the intended trajectory of the golf ball""s flight. There are two general methods for analyzing the golf club during a golf swing: visual analysis and quantitative variable analysis.
The method of analyzing a golf club during a golf swing using visual analysis typically is conducted by a golf instructor capable of visually discerning golf swing variables, and suggesting corrections in the golfer""s swing to provide improvement. However, not every golfer has ready access to professional golf instruction. The golfer also can diagnose certain swing faults using visual analysis methodology employing one or more cameras to record the golfer""s swing and comparing it to a model swing. Using various camera angles and slow motion play back, the actual swing motion can be reviewed and altered in subsequent swings.
On the other hand, quantitative variable analysis employs sensors to directly measure various mechanical or physical properties of the golf club during the swing motion. Sensors, such as strain gauges or accelerometers, typically are attached to the shaft or the golf club head. Data collected from these strain gauges then may be transferred to a signal processor via wires or radio waves, and can be presented in various graphical formats, including graphical and tabular charts. A significant drawback associated with the use of wires in an instrumented golf club is that the wires can be very cumbersome, and can become obtrusive to the golfer when the golfer attempts to swing the golf club. Several different approaches to analyzing a golf club or baseball bat during a baseball or golf swing using quantitative variable analysis are discussed in the patents listed below.
For example, in U.S. Pat. No. 4,759,219, issued to Cobb et al., the specification discloses a baseball bat with a self-contained measuring device and display. A spring potentiometer is used to measure centrifugal force, and an LED or LCD displays the measured force. However, this bat does not contain any data storage capability.
U.S. Pat. No. 5,233,544, issued to Kobayashi, discloses a golf club having multiple sensors, and a cable for transmitting data to a computer for data processing. This arrangement can accommodate up to 5 sensors in a cartridge located in the handle region of the golf club.
U.S. Pat. No. 3,182,508, issued to Varju, discloses the use of a strain gauge in the bottom of a golf club, and a wire for connecting the sensor to a data processing means located separate from the golf club.
U.S. Pat. No. 5,694,340, issued to Kim, discloses the use of multiple sensors for measuring the acceleration of a golf club, and uses either a cable or radio transmissions to transfer data from the sensors to an external data processing means.
U.S. Pat. No. 4,991,850, issued to Wilhelm, discloses the use of a sensor for measuring the applied force of a golf swing. The sensor data can be displayed on a wrist-mounted arrangement or be downloaded to a computer via cable or radio transmission.
U.S. Pat. No. 3,792,863, issued to Evans, discloses the use of multiple sensors, including an accelerometer and strain gauges, to measure torque and flex. Data is transferred from the golf club to a data analysis station via FM radio signals, with each sensor having its own data transfer frequency.
Thus, data transfer to an external memory device is a significant drawback. The cumbersome nature of data transfer via cables or wires affects the motion and feel of a golfer""s actual golf swing. In addition, while the use of radio transmissions is preferable to the use of wires or cables emanating from the golf club for transferring data, a transmitter adds excessive weight. The effective range of these wireless instrumented golf clubs is limited by the low power used in such embodiments, and the accuracy of the radio transmitted data is subject to interference or noise from other sources of nearby radio transmissions.
Furthermore, in conventional systems, the receiving equipment typically must be located in close proximity to the radio transmitter disposed in the golf club thereby restricting the flexibility and portability of using such systems. Thus, it is desirable to provide an instrumented golf club that approximates the weight, balance and feel of a golfer""s own golf club, in order to ensure that the data collected from the instrumented golf club is applicable to the golfer""s actual golf swing. It also may be desirable to provide additional sensors for measuring certain parameters of a golf swing that have previously not been available in instrumented golf clubs. It further may be desirable to provide an efficient means of memory storage within the instrumented golf club to enable internal data capture and storage until the user is ready to download the data for further processing. It further may be desirable to provide data from the instrumented golf club for golf club design.
The diagnostic golf club of the present invention comprises an internally powered and instrumented golf club with multiple strain gauges to measure, store, and provide an external display of quantitative variables of a golf club during a golf swing. A distinctive feature of the diagnostic golf club of the present invention is the use of a data storage memory device located within the shaft of the golf club, which is capable of receiving and storing data received from the plurality of strain gauges located on the club. The use of an internal memory device eliminates the need to use radio transmission hardware, data cables or wires to transfer data to an external data processing means. This also allows a golfer to swing the instrumented golf club without getting entangled in cables or wires, thus better allowing the golfer to replicate his or her natural golf swing.
In a preferred embodiment, swing data in the form of digitized signals are stored in a non-volatile flash buffer memory. The use of non-volatile memory insures that data is not lost if the system is turned off or in the event the battery fails. Because a ring buffer memory is used, it is still possible to replace older data with new data during successive cycles. The use of a ring buffer memory device provides for the creation of an instrumented golf club that is lightweight and free of cables or radio transmitters. Using a linear data capture approach, as taught by the prior art:, would require extensive amounts of memory, and would make it very difficult to provide such memory requirements completely internal to an instrumented golf club. It is through the use of the ring buffer memory that one is able to efficiently capture the desired swing data of interest, such as impact with a golf ball, and eliminate the need to provide internal memory to capture data unrelated to a golfer""s swings.
Furthermore, since the ring buffer memory captures only the desired swing data of interest, data for multiple swings can be stored in the memory device of the instrumented golf club of the present invention until the user decides to upload the information to a computer unit for processing. Uploads can be effected via an interface mechanism located within the shaft. The interface provides for the electronic communication of data between the golf club and a computer unit. This provides increased flexibility and mobility to the user since the user is not required to stay within close physical proximity to the external data processing means.
In addition to the internal memory device, electronic circuitry consisting of a circuit board comprising a power control circuit, a signal conditioning circuit for the plurality of sensors and a serial communication circuit are located within the hollow interior of the shaft. Having these features incorporated into the circuit board allows downloading of high-level digital signals as well significantly reducing noise corruption and enables data to be stored indefinitely on the club. Locating the circuit board and components within the shaft also increases protection from shock loadings typically experienced upon ball impact when the circuitry is placed upon the golf club head.
In addition, incorporation of an internal power source for the instrumented golf club of the present invention is preferred for providing the benefits of flexibility and mobility. The internal power source can also be used to provide a proper weight balance, or swing weight, for the instrumented golf club, thereby closely approximating the golfer""s own golf club. Although the internal power source can be placed in various locations within the instrumented golf club, in a preferred embodiment, a battery tube and one or more batteries are located within the shaft.
A preferred embodiment of the instrumented golf club system of the present invention comprises a first plurality of strain gauges located at an exterior tip end of the golf club shaft. A second plurality of strain gauges are located at an exterior butt end of the golf club shaft. In a preferred embodiment the plurality of strain gauges comprise two sets of three rosettes. Each rosette group containing gauges having a central bend gauge and two crossing shear gauges. The rosette groups arranged such that they form six individual Wheatstone bridges. Additionally, while it is preferable to locate individual rosette groups 120xc2x0 from each other rosette group, those skilled in the pertinent art will recognize that distribution locations of the strain gauge rosette groups around the exterior perimeter of the golf club shaft is not critical and that distribution may be adjusted to achieve a desired placement distribution without departing from the scope and spirit of the present invention.
The system further comprises a circuit board positioned within the interior of the shaft comprising a memory circuit for storing the strain measurements, a power control circuit, a first signaling conditioning unit for the first plurality of strain gauges, a second signaling conditioning circuit for the second plurality of strain gauges, and a serial communication unit. The circuit board is connected via a first plurality of wires to the first plurality of strain gauges and via a second plurality of wires to the second plurality of strain gauges. A power source as previously described is positioned within the interior of the shaft for providing power to the circuit board, the first plurality of strain gauges and the second plurality of strain gauges.
Once the swing data has been obtained by the strain gauges and stored in the memory, a processor may be used to retrieve the stored memory from the instrumented golf club via an interface mechanism used to permit communication from the instrumented golf club to the processing unit. The retrieved data can then be used to provide a shaft flex profile for a golfer.
Furthermore, the strain and bend measurements stored by the instrumented golf club system of the present invention may be converted to a variety of measurements including axial force, transverse shear forces, bending moments, and torsion of the club during the swing. These measurements can also be used to generate a shaft flex profile for a golfer.
Through the use of an external data means, the instrumented golf club system enables quantitative swing data to be captured, transferred to the processing means, and then presented in any number of graphical, tabular or other visual formats to provide a golfer with meaningful feedback regarding the dynamics of a golf swing.
In addition, the instrumented golf club system. of the present invention can be used as a design tool for golf clubs including investigation of such variables as club head geometry, shaft dynamics, structural material behavior and type and location of weighting materials. As an example, the effect of different club head weighting locations can be measured for a wide range of golf swings to provide improved performance within this range of swings.
Accordingly, it is an object of the present invention to provide an instrumented golf club capable of measuring and storing data within the instrumented golf club without the use of an intermediate conduit such as external data transfer cables, wires or radio transmissions, thereby allowing greater flexibility and mobility to a user of the instrumented golf club.
It is a further object of the present invention to provide an instrumented golf club with non-volatile memory so that the memory is not lost if the club is turned off or the battery is removed.
It is a further object of the present invention to provide an instrumented golf club capable of converting a series of strain measurements to a series of force and bending moments in order to generate a shaft flex profile for a golfer.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.